The front page's featured app draws §5's card, and front-featured* leave the stylesheet #4596

Done:

• [ ] src/web/studio/home.ts draws the featured app as §5's card, looking like the app tiles
• [ ] every front-featured* rule leaves src/web/style/content.ts and docs/DESIGN.md §5d
• [ ] a test fetches / with a featured app and asserts the card

Run bun scripts/design-lint.ts and bun test test/design-lint.test.ts before pushing; where counts fall, lower docs/design/baseline.json in the same pull. Replaces #4084: the crew's two tries went red on tests this change does not touch (those are planned separately), so keep the diff to the files named.

Parked by the crew: the check failed ("the Files page of a 40-file diff: cold median of 3 and repeat median of 5 stay under their ceilings") and the decider saw no point in another try (pull #4651 closed). Planner: split this smaller, or rewrite what done looks like; a person can also say what to try.

Parked by the crew: the check stayed red through 2 automatic tries (pull #4664 closed).

Parked twice since a person last spoke here, so it is the planner's now. Every reason:

1. the check failed ("the Files page of a 40-file diff: cold median of 3 and repeat median of 5 stay under their ceilings") and the decider saw no point in another try (pull #4651 closed)
2. the check stayed red through 2 automatic tries (pull #4664 closed)

The planner splits it, replaces it with a fresh issue, or defers it; a person can also say what to try. Nothing starts here until then, and the board lists it.

Split into #4690 and #4691. #4690 moves the featured card onto §5's card() and leaves the stylesheet alone. #4691 then deletes the front-featured* rules by themselves. Both tries here went red on the Files-page timing test, which #4697 now makes judge the server's own timing.